"""Poll module is ungraded xmodule used by students to
to do set of polls.

On the client side we show:
If student does not yet anwered - Question with set of choices.
If student have answered - Question with statistics for each answers.
"""

import cgi
import json
import logging
from copy import deepcopy
from collections import OrderedDict

from lxml import etree
from openedx.core.djangolib.markup import Text
from pkg_resources import resource_string

from xmodule.x_module import XModule
from xmodule.stringify import stringify_children
from xmodule.mako_module import MakoModuleDescriptor
from xmodule.xml_module import XmlDescriptor
from xblock.fields import Scope, String, Dict, Boolean, List

log = logging.getLogger(__name__)
_ = lambda text: text


class PollFields(object):
    # Name of poll to use in links to this poll
    display_name = String(
        help=_("The display name for this component."),
        scope=Scope.settings
    )

    voted = Boolean(
        help=_("Whether this student has voted on the poll"),
        scope=Scope.user_state,
        default=False
    )
    poll_answer = String(
        help=_("Student answer"),
        scope=Scope.user_state,
        default=''
    )
    poll_answers = Dict(
        help=_("Poll answers from all students"),
        scope=Scope.user_state_summary
    )

    # List of answers, in the form {'id': 'some id', 'text': 'the answer text'}
    answers = List(
        help=_("Poll answers from xml"),
        scope=Scope.content,
        default=[]
    )

    question = String(
        help=_("Poll question"),
        scope=Scope.content,
        default=''
    )


class PollModule(PollFields, XModule):
    """Poll Module"""
    js = {
        'js': [
            resource_string(__name__, 'js/src/javascript_loader.js'),
            resource_string(__name__, 'js/src/poll/poll.js'),
            resource_string(__name__, 'js/src/poll/poll_main.js')
        ]
    }
    css = {'scss': [resource_string(__name__, 'css/poll/display.scss')]}
    js_module_name = "Poll"

    def handle_ajax(self, dispatch, data):
        """Ajax handler.

        Args:
            dispatch: string request slug
            data: dict request data parameters

        Returns:
            json string
        """
        if dispatch in self.poll_answers and not self.voted:
            # FIXME: fix this, when xblock will support mutable types.
            # Now we use this hack.
            temp_poll_answers = self.poll_answers
            temp_poll_answers[dispatch] += 1
            self.poll_answers = temp_poll_answers

            self.voted = True
            self.poll_answer = dispatch
            return json.dumps({'poll_answers': self.poll_answers,
                               'total': sum(self.poll_answers.values()),
                               'callback': {'objectName': 'Conditional'}
                               })
        elif dispatch == 'get_state':
            return json.dumps({'poll_answer': self.poll_answer,
                               'poll_answers': self.poll_answers,
                               'total': sum(self.poll_answers.values())
                               })
        elif dispatch == 'reset_poll' and self.voted and \
                self.descriptor.xml_attributes.get('reset', 'True').lower() != 'false':
            self.voted = False

            # FIXME: fix this, when xblock will support mutable types.
            # Now we use this hack.
            temp_poll_answers = self.poll_answers
            temp_poll_answers[self.poll_answer] -= 1
            self.poll_answers = temp_poll_answers

            self.poll_answer = ''
            return json.dumps({'status': 'success'})
        else:  # return error message
            return json.dumps({'error': 'Unknown Command!'})

    def get_html(self):
        """Renders parameters to template."""
        params = {
            'element_id': self.location.html_id(),
            'element_class': self.location.category,
            'ajax_url': self.system.ajax_url,
            'configuration_json': self.dump_poll(),
        }
        self.content = self.system.render_template('poll.html', params)
        return self.content

    def dump_poll(self):
        """Dump poll information.

        Returns:
            string - Serialize json.
        """
        # FIXME: hack for resolving caching `default={}` during definition
        # poll_answers field
        if self.poll_answers is None:
            self.poll_answers = {}

        answers_to_json = OrderedDict()

        # FIXME: fix this, when xblock support mutable types.
        # Now we use this hack.
        temp_poll_answers = self.poll_answers

        # Fill self.poll_answers, prepare data for template context.
        for answer in self.answers:
            # Set default count for answer = 0.
            if answer['id'] not in temp_poll_answers:
                temp_poll_answers[answer['id']] = 0
            answers_to_json[answer['id']] = cgi.escape(answer['text'])
        self.poll_answers = temp_poll_answers

        return json.dumps({
            'answers': answers_to_json,
            'question': cgi.escape(self.question),
            # to show answered poll after reload:
            'poll_answer': self.poll_answer,
            'poll_answers': self.poll_answers if self.voted else {},
            'total': sum(self.poll_answers.values()) if self.voted else 0,
            'reset': str(self.descriptor.xml_attributes.get('reset', 'true')).lower()
        })


class PollDescriptor(PollFields, MakoModuleDescriptor, XmlDescriptor):
    _tag_name = 'poll_question'
    _child_tag_name = 'answer'

    module_class = PollModule
    resources_dir = None

    @classmethod
    def definition_from_xml(cls, xml_object, system):
        """Pull out the data into dictionary.

        Args:
            xml_object: xml from file.
            system: `system` object.

        Returns:
            (definition, children) - tuple
            definition - dict:
                {
                    'answers': <List of answers>,
                    'question': <Question string>
                }
        """
        # Check for presense of required tags in xml.
        if len(xml_object.xpath(cls._child_tag_name)) == 0:
            raise ValueError("Poll_question definition must include \
                at least one 'answer' tag")

        xml_object_copy = deepcopy(xml_object)
        answers = []
        for element_answer in xml_object_copy.findall(cls._child_tag_name):
            answer_id = element_answer.get('id', None)
            if answer_id:
                answers.append({
                    'id': answer_id,
                    'text': stringify_children(element_answer)
                })
            xml_object_copy.remove(element_answer)

        definition = {
            'answers': answers,
            'question': stringify_children(xml_object_copy)
        }
        children = []

        return (definition, children)

    def definition_to_xml(self, resource_fs):
        """Return an xml element representing to this definition."""
        poll_str = u'<{tag_name}>{text}</{tag_name}>'.format(
            tag_name=self._tag_name, text=self.question)
        xml_object = etree.fromstring(poll_str)
        xml_object.set('display_name', self.display_name)

        def add_child(xml_obj, answer):
            # Escape answer text before adding to xml tree.
            answer_text = unicode(Text(answer['text']))
            child_str = u'<{tag_name} id="{id}">{text}</{tag_name}>'.format(
                tag_name=self._child_tag_name, id=answer['id'],
                text=answer_text)
            child_node = etree.fromstring(child_str)
            xml_object.append(child_node)

        for answer in self.answers:
            add_child(xml_object, answer)

        return xml_object
